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Old 06-23-2013, 02:37 PM   #1
Mordecai
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Default Datalog Prob - AF learning 1a Positive - Intermittent FLK & FBK

I will try to provide the most detailed and comprehensive post to help try and figure out some of these issues I seem to be constantly having. Here is some background - the car is a 2005 Forester XT with the following mods:

-VF48
-Accessport v2 w/protune by Jorge @ IAG Performance
-DW950cc sidefeed injectors (see this thread http://forums.nasioc.com/forums/show....php?t=1769552)
-APS cai 65mm w/amsoil dry cone filter - cleaned maf
-new front o2 that was put in before the protune.
-3in turboback exh
-Turbo XS TMIC
-Grimspeed BCS
-Deatschwerks Fuel Pump
-NGK 1 step colder plugs
-LC1 Innovate WB 12inches behind the turbo (new bung welded in)

The car was tuned with good results. However, shortly thereafter, I started having problems with the AF Learning 1a trims. The ecu continued to pull fueland would eventually max out at -15% within the course of a day. Tuner took another look at it and figured out that it was due to the scaling of the injectors. Once he adjusted it to fit the profile of the usual dw850ccs, the trims returned to normal +/- 3%. For the next few weeks the idle trims stayed within that range.

Fast forward a few months later, I do some datalogging to try and gather data to send to the tuner due to some lingering issues the car had every since the last time it was tuned - the car would basically intermittently die when coming to a fast stop with brake and clutch depressed. Well to my surprise, the AF Learning 1a trims are not very high. Throughout the day, I would see anywhere from +4 to +12%. I also did some wot datalogs to see how everything else was dialed in and it seems as if I have some FBK & FLK. But then later that night, I did another datalog with a 3rd and 4th gear pull with no knock at all and with a AF Learning 1a of around +5%.

I've attached some datalogs below. First datalog is just idling with the high AF Learning 1a.

The next datalogs are of wot pulls. The first 2 have some knock, the 3rd and 4th seems fine as far as I can tell.

What I don't understand is that why the car thinks I am running lean at idle and thus adding fuel. My wideband and the front O2 will show at idle around 13.9-14.2 max. If anything I would think I would see a negative value but I see that the AF Correction is positive in real time. What also confuses me is that while AF correction 1 is say 3-5%, the AF learning 1 is 10% - why the disparity? Isn't the AF learning 1 supposed to be based upon the AF Correction 1?

As for the knock, I'm thinking that its a fluke? When I see the Fine Learned Knock, there doesn't seem to be any Feedback Knock. When theres some feedback knock, theres no fine learned?

When I asked for a tune, I wanted very safe and conservative tune. I basically wanted some more power, but planned to make the car more of a casual autocrosser and grocery getter with some gittyup.

I've started to slowly research into tuning myself, but as a professional that with limited time, this is difficult to do. Despite this, I try to do most things on the car myself ei. timing belt, power steering pump rebuild, bushings, etc. But I KNOW that I don't know enough about tuning a car safely and thus paid someone to do this. However, I just hate the feeling of now "knowing" how the "magic" of tuning works on this car. I suppose I have a need (that many of you are familiar with no doubt) to know how everything works on our cars.

Anyway, very frustrating few months I've had. Any insight/help would be appreciated. I'd like to troubleshoot before replacing (anymore) parts.

https://docs.google.com/spreadsheet/...lE&usp=sharing

https://docs.google.com/spreadsheet/...Gc&usp=sharing

https://docs.google.com/spreadsheet/...Gc&usp=sharing

https://docs.google.com/spreadsheet/...Gc&usp=sharing

https://docs.google.com/spreadsheet/...VE&usp=sharing

Sorry, links fixed
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Last edited by Mordecai; 06-25-2013 at 11:39 AM.
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Old 06-25-2013, 01:20 AM   #2
esteve
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I would think you have a vacuum leak if A/F learning 1A goes up to +12%. Maybe you have an injector o-ring that's not seated correctly or maybe it's pinched? Are you still on your stock turbo inlet? Those things are garbage and are known to tear over time. I'd also check the brake booster hose since your car stalls when you brake...who knows maybe the big TMIC is chaffing and made a hole in it. Another possible symptom is if it takes more brake pedal pressure to stop.

I would think your wideband readings at idle would be much higher than 14:1 too but maybe the computer is trying to adjust. You might also want to check your AFRs at cruise to see if they're lean.

You've probably already read this but here's a link to a very nice write-up regarding vacuum leaks:
http://www.romraider.com/forum/viewt...hp?f=33&t=7202

BTW, not that I would be of much help with them but your links don't work.
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Old 06-25-2013, 11:45 AM   #3
Mordecai
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Thanks for the link - I had not seen that yet and it is very helpful. My links are fixed now.

It is not a stock inlet - its an avo. I'll check the brake booster and lines. The car will never be lean at idle or cruising, which makes me think its not a vacuum leak. I'm thinking maybe its the injector latency or maf scaling?
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Old 06-25-2013, 12:21 PM   #4
nmlittlebigman
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Your wideband may not read lean at idle and cruise because like Steve said your ecu is making the corrections (adding fuel). AF correction 1 + AF learning 1 = total fueling corrections. They are cumulative. If your AF learning is already high your AF correction may not need to be very large.

As for knock, FBKC and FLKC are two separate and independent controls. FBKC generally is enabled when your load is rapidly changing. It's a here and now type thing and the ecu does not store the correction.

FLKC is enabled when load is not changing as fast or is somewhat static, and as its name implies the ecu "learns" to pull timing in those rpm/load ranges. FLKC is unlearned too if there's no perceived knock.

Generally if you fuel trims (AF learning) were good before and suddenly change to high positive values at idle then you have developed a vacuum leak. To rule that in/out you need perform a leak test of your intake tract.
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Old 06-25-2013, 02:53 PM   #5
Mordecai
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In terms of the correction, what I don't understand is that as I'm looking at the AFR as it read 14.0, I can literally watch it go from +3% to +11% in AF learning and AF Learning 1a. I can understand if the AFR was something like 15.0, but its not. I'm starting to think this is an injector or maf tuning issue.
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Old 06-25-2013, 03:06 PM   #6
Mordecai
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Heres a new piece of info. When I adjust the idle from 1000 to 1200 through my accessport, the AF learning 1a will go down.
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Old 06-25-2013, 06:59 PM   #7
nmlittlebigman
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Quote:
Originally Posted by Mordecai View Post
Heres a new piece of info. When I adjust the idle from 1000 to 1200 through my accessport, the AF learning 1a will go down.
That's not surprising. Your ecu doesn't have much stored learning for that range. I bet your AF Correction #1 (short term fuel trims) is making up for it. Remember they are added together to make the adjustment.
The objective of AF Learning #1 is to minimize the amount of short term corrections needed. That's why most people will tell you to run through a couple of tanks of gas after a reflash to allow the data to populate before checking your AF Learning (long term fuel trims).

You have a mechanical issue causing this, most likely a vacuum leak.
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Old 06-25-2013, 07:27 PM   #8
Mordecai
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I'm going to leak test it again tomorrow and see if I can find something. Hopefully thats all it is.
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Old 06-25-2013, 08:56 PM   #9
nmlittlebigman
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Good luck. I have also seen a torn or pinched o-ring for the maf sensor cause similar issues. Hope to hear back that you got it figuired out.
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Old 07-25-2013, 11:13 AM   #10
Mordecai
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Just to follow up, no mechanical issues have been found. Leak tests have been done and the system has help +15psi. The tuner will be taking another look at it this weekend and has thus given me a new map that also increased the idle air settings.

Since then I've put roughly 700 miles of mixed driving. I've made it a point to drive the car through the various closed loop airflow trims (AF Learning A-C). The car will still intermittently die when coming to a quick full stop with the clutch in and the AC on.

The AF Learning 1A seems better, but now AF Learning 1B is ridiculously off as you can see.

https://docs.google.com/spreadsheet/...Xc&usp=sharing

https://docs.google.com/spreadsheet/...FE&usp=sharing

Now as many of you know, the AF Learning 1B trim only accounts for CL fueling within the range of 5-10g/s. I noticed that I only got in this range when I was in cruise control and either had no incline or the car was going slightly downhill - thus required barely any throttle. At this point, my wideband AF was reading 12-13afr. This makes sense as to why the ecu is at -14.x% now as it tries to pull fuel away from this range. However, now due to this learned correction, at some other times when I"m in this range, my AFR will hit 15.x for a second. Very frustrating.
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Old 07-25-2013, 12:16 PM   #11
nmlittlebigman
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I know your first post stated that you cleaned your maf sensor, but it might be worthwhile to replace it or borrow one for a short bit and compare the two.

good luck
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Old 07-25-2013, 01:06 PM   #12
Mordecai
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I can try to find someone who'd be willing to swap for a bit but I can't keep buying parts anymore. This is after both o2s were replaced (both were fine) as well. Theres no CE light or overt signs of MAF failure as well as evidenced by looking at the MAF signal, g/s. The idle doesn't bounce around or act erratically. Its the fuel trims that are off. This can certainly be d/t a MAF, I just don't see any signs that thats the case, especially w/ the AF Learning 1B trims being the area now that is grossly off.
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